BMW X5 Back Up Light Bulb Size

The BMW X5 back up light utilizes 921 and P21W bulb sizes for the rear illumination components. Available data covers the specific range from 2000 through 2013 for the mentioned vehicle.

The year-by-year compatibility chart below provides a quick reference to verify the correct bulb size for your vehicle.

Bulb Size by Year Range

Years	Bulb Size
2007-2013	921
2000-2006	P21W

Bulb Specifications

Description	Bulb Size
ANSI standard (US & Canada). Wedge bulb (T15). 12V, 16W.	921
ECE standard (Europe & worldwide). Single-filament signalling bulb with BA15s bayonet base. 12V, 21W.	P21W

Other Locations

Additional Notes

The BMW X5 back up light specifications cover model years 2000-2013 and reference two distinct bulb types: the 921 and the P21W.
The 921 is an ANSI-standard bulb used primarily in the United States and Canada. It is a T15 wedge-base bulb rated at 12V and 16W.
The P21W follows the ECE standard, which governs lighting regulations across Europe and much of the world. It is a single-filament bulb with a BA15s bayonet base, rated at 12V and 21W.
The BA15s bayonet base of the P21W is not interchangeable with the wedge base of the 921, as the two bulbs use fundamentally different mounting systems.
The BMW X5 (2007-2013) uses the 921 bulb for the back up light position.
The 2000-2006 model years use the P21W, reflecting the ECE-standard lighting configuration common to European-market vehicles during that generation.
The P21W operates at 21W, which is 5W higher than the 921. This wattage difference means the two bulbs are not electrically equivalent and should not be treated as substitutes for one another.
The shift from P21W to 921 between the 2006 and 2007 model years corresponds to a generational change in the X5 platform, which brought a transition from ECE-standard to ANSI-standard bulb fitment in this position.